In recent years, there have been proposed flat panel display apparatuses in which phosphors are irradiated with electron beams emitted from electron emission sources, such as field emission devices, to cause the phosphors to emit light, and thereby forming an image, such as a field emission display (hereinafter abridged to FED).
In an FED, a substrate provided with electron emission sources arranged in a matrix form and a substrate provided with phosphors are disposed opposite to each other with a minute gap therebetween, the peripheries of the substrates are sealed to form a gas-tight container, the inside of the gas-tight container is maintained in a high vacuum or an ultrahigh vacuum, and the phosphors are irradiated with electron beams emitted from electron emission sources to cause the phosphors to emit light, and thereby displaying an image.
For an assured operation of the FED, it is necessary to maintain the inside of the gas-tight container formed between the substrates in an ultrahigh vacuum (a pressure of not higher than about 1×10−6 Pa). This is because, at a lower degree of vacuum (namely, at a higher pressure), field emission devices used as the electron emission sources are contaminated, leading to a trouble regarding the electron emission characteristics (emission characteristics) and shortening the life of the FED.
Thus, in a flat panel display apparatus including therein a gas-tight container with a high degree of vacuum, such as the FED, a vapor-deposition-type getter is disposed inside a getter chamber disposed at an end portion of the gas-tight container, in order to enhance the degree of vacuum inside the gas-tight container by the gettering effect. In addition, provision of a non-evaporation-type getter inside the gas-tight container also has been proposed.
In the flat panel display apparatus, such as the FED, the gap between a front substrate and a back substrate is as minute as about 1.5 mm or less, and it is difficult to bring the inside space to an ultrahigh vacuum, but it is important to maintain all locations in the inside space at a uniform degree of vacuum. Besides, in an operation of the FED, the irradiation of a phosphor surface with electrons discharged from the field emission devices causes liberation of a gas or gases. When a gradient of the degree of vacuum is generated as a result of the liberation of a gas or gases, the region where the field emission devices are formed on the back substrate the field emission devices may be contaminated depending on the location, and the emission characteristics at the contaminated portions are degraded, resulting in a shortening of the life of the FED. Therefore, with only the vapor-deposition-type getter disposed only at an end portion of the gas-tight container, generation of a gradient of the degree of vacuum cannot be obviated. In view of this, in the flat panel display apparatuses such as the FED, the need to dispose non-evaporation-type getters in a dispersed manner has been increasing, in order to maintain the inside of the gas-tight container at a uniform ultrahigh vacuum.
Conventionally, the non-evaporation-type getters have been formed by vapor deposition or sputtering. In the formation of the non-evaporation-type getters, it is necessary to form the non-evaporation-type getters at positions for avoiding the field emission device pattern and the phosphor pattern, resulting in a difficulty on a manufacturing process basis that an accurate masking treatment is needed. If the masking is unsatisfactory and the field emission devices are contaminated due to vapor deposition or the like, a trouble as to emission characteristics is generated, and the life of the flat panel display apparatus, such as the FED, is shortened.
Incidentally, there have also been proposed some methods of forming non-evaporation-type getters by a film forming process other than vapor deposition and sputtering. For example, Japanese Patent Laid-open No. Hei 5-159697 proposes a method of producing a non-evaporation-type getter by a powder processing molding or powder press molding sintering technique.
According to the method disclosed in the publication, however, cracking or deformation is liable to occur at the time of sintering due to such causes as a distribution of the shrinkage factor, so that there is the limitation that it is impossible to form a non-evaporation-type getter having a complicated shape. Besides, the powder molding leads to the problem of dusting.
As a method of disposing and fixing a non-evaporation-type getter formed by the powder press molding sintering technique or the like in the inside of a flat panel display apparatus, there has been proposed a method of fixing the non-evaporation-type getter by use of an adhesive, as disclosed, for example, in Japanese Patent Laid-open No. 2000-311638. In the method, however, it is difficult to achieve masking at the time of applying the adhesive. Besides, depending on the kind of adhesive, a gas may be liberated from the adhesive during or after a thermal activating treatment of the getter, leading to a lowering of the gas absorbing capability of the getter or to contamination of the field emission devices, with the result of degradation of the emission characteristics. In addition, to obviate such an inconvenience, it is necessary to devise a measure for preventing the liberation of gas from the adhesive.
Thus, particularly in a flat panel display apparatus, it has been very difficult to dispose the non-evaporation-type getter.
The present invention has been made in consideration of the above-mentioned circumstances. Accordingly, it is a first object of the present invention to provide a non-evaporation-type getter which is excellent in gettering effect, capable of maintaining the inside of a gas-tight container in a display apparatus, particularly in a flat panel display apparatus or the like, in a high vacuum condition, easy to mount and less liable to contaminate the inside of the gas-tight container, a display apparatus including the getter, and methods of manufacturing the same.
It is a second object of the present invention to provide a flat display apparatus capable of enhancing the reliability characteristic of emission of electron beams from electron emission sources, such as field emission devices, and contriving a longer life, and a method of manufacturing the same.